Railway traffic controlling apparatus



May 19, 1931. A. J. SORENSEN RAILWAY TRAFFIC CONTROLLING APPARATUS FiledFeb. 7, 1950 4 Sheets-Sheet 1 INVENTOR;

f! T. oren sen,

% eta-M y 1931- A. J. SORENSEN 1,806,092

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Feb. "7, 1950 4 Sheets-Sheet2 INVENTORZ /Q.J' Sore/user May 19, 1931. A. J. s'oRENsEN RAILWAYTRAFFIC CbNTROLLIfiG APPARATUS Filed Feb. 7, 1930 4 Sheets-Sheet 3 n 6 6n 2 m m5 N H A. J. SQRENSEN 1,806,092

May 19, 1931.

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Feb. 7. l930 4 Sheets-Sheet4 l E .3% 1 95 5% 25 r: 56 D-1 95b 5 4'87 7 '45 INVENTOR. H. I.Sorenscn,-

' characters 1 and 1 'persecond.

Patented May 19, 1931 are r OFFICE ANDREW J". SORENSEN, OF PITTSBURGH,PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OFSWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA RAILWAY.TRAFFICCONTROLLING APPARATUS Application filed February 7, 1930. Serial No.426,583.

My invention relates to railway traflic controlling apparatus, andparticularly to apparatus of the type comprising train carried governingmeans controlled by energy re ceived from the trackway.

The present case is a continuation in part of my co-pending application,Serial N0. 238,572, filed Dec. 8, 1927, for railway traific controllingapparatus, in so far as the subject matter common to the twoapplications is concerned.

I will describe several forms of railway tratfic controlling apparatusembodying my invention, and will then point out the novel featuresthereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view showing oneform of railway tratfic controlling apparatus embodying my invention'Fig. 2 is a view showing a modified form of the train carried portion ofthe apparatus shown in Fig. 1. Fig. 3 is a view'showing in frontelevation one form of oscillator forming a part of the apparatusillustrated'in Fig. 1. Figs. 4 and 5 are views showing in top plan andend elevation, respectively, the oscillator of Fig. 3. Fig. 6 is avertical transversesectional View along the lines VI-VI of Fig. 3. Fig.

7 is a view similar to Fig. 5, showing a modified form of a portion ofthe oscillator. Fig. 8 is a view showing a modified form 01 theapparatus illustrated in Figs. 1 and 2.

Similar reference. characters refer to similar parts in each of theseveral views.

Referring first to Fig. 1, the reference designate the track rails of astretch of railway track over which trafiic normally moves in thedirection indicated by the arrow. These rails are divided, by means ofinsulated joints 2, into a plurality of successive track sections, onlyone of which, AB, is shown complete in the drawing. Train controllingcurrent is supplied to the rails of this section from a suitable sourceof energysuch as an alternate or G. The current supplied to the trackwayby this alternator may be of a frequency of the order of the usualcommercial alternating current, such for example as cycles or 100 cyclesconnected with the raill The supply of current to the track rails iscontrolled by a coding device designated in general by the referencecharacter X and comprising a plurality of rotatable cams each designatedby the reference character C with a suitable distinguishing exponent.The cams C are driven at aconstant speed by a suitable motor M which issupplied with The cam C contacts3, 4, or 5, conditions. i I

It is manifest that the alternating current supplied to the rails of thetrackway by depending upon traffic alternatorG is periodically varied atthe frequency of operation of the contact of the device X that isinterposed between the alternator and the trackrail 1 The coding deviceX may be constructed to cause such variations at any reasonablefrequencies, but for purposes of illustration, I will assume that thecams C are rotating at 20 revolutions per minute, that'cam C has 4swells, that cam C has 6 swells, and that cam C has 9 swells. Theselection between the several contacts of the coding device X inaccordance with trafic conditions may be accomplished in any suitablemanner such,'for example, as by means of a home relay H and a distantrelay L. The circuits for controlling these two relays form'no part ofmy present invention and are omitted from the drawing for the sake ofsimplicity. For

present purposes it is suificient to state. that home relay H isnormally deenergized when a train occupiesthe section immediately to theright of point B.

through one of the energized but is The distant relay L is also normallyenergized but is deenergized when a train occupies either the first orthe second section with a winding 12, and w1th a winding 12,

immediately to the right of point B. With the apparatus thus fardescribed, when relays H and L are both energized so that front contact(5-6 of relay H and front contact 7-7" 0f relay L are closed, currentfrom alternator G, which current I will assume to be of 100 cycles persecond, is supplied to the track rails over contact 5 operated by cam CUnder these conditions the alternating current supplied to the trackwayis periodically varied at a frequency of 180 cycles per minute. Currentsupplied to the trackway under these conditions, I will hereinafter termthe proceed code. -"When relay H is energized and relay L isdeenergized, the closing of back contact 7-? of relay L includes contact4; controlled-by cam C in the trackway circuit, and under theseconditions the trackway is supplied with 100 cycle current interruptedat a frequency of 120 cycles per minute; this current I shallhereinafter term the caution code. In similar manner when relay H isdeenergized, the closing of back contact6-6 of this relay completes acircuit from alternator G to the track rails through contact 3 operatedby cam C Under these conditions the trackway is supplied with 100 cyclecurrent interrupted at a frequency of 80 cycles per minute, whichcurrent I will call the slow code.

' The train indicated diagrammatically at V is provided with governingmeans which is responsive tothe frequency of the periodic variations inthe 100 cycle current supplied to the trackway. In the presentembodiment of my invention the train is provided With two magnetizablecores 11 and 11 located in advance of the forward axle 10 and disposedin inductive relation with the two track rails 1 and 1*, respectively.Core 11 is provided a core 11 is provided the two windings 12 and 12being connected in series in suchmanner that the voltages inducedtherein by train controlling current flowing-in opposite directions inthe track rails at any instant are additive. \Vindings 12 and 12areconnected, through an amplifier 13, and a transformer Q, with apolarizedzrelay It. When train controlling current is being supplied tothetrackway,pulsating energy is delivered to the primary of transformerQ at the fre- :quency of the periodic variations in such trackwaycurrent. For each impulse ofcurrent supplied to transformer Q,Cluringthe increase of such current, an impulse of one relative polarityis supplied to relay R and during the decrease of such current, animpulse of'the opposite relative polarity is sup- 2 plied to the relay.The relay R is responsive to the relative polarity ofthe current sup-.plied" thereto and train controlling current is supplied to thetrackwayis being periodically varied, the :.-r.elay,R is operated toclose itsnormal and it follows that when the .of fly wheels .bars 20 and21 of reverse contacts 15-15 and 1515 alternately at a frequency whichcorresponds to the frequency of the variations of the trackway current.

Associated with relay R is an oscillator designated by the referencecharacter K. Beferring now also to Figs. 3 to 6 inclusive, theoscillator comprises a base 16 carrying an electromagnet Ewhich operatesa pivoted armature 19. A permanent magnet 18 extends from the back strap17 of the electromagnet Etc a position above the armature 19, for thepurpose of polarizing the armature. The armature 19 constitutes one endof a driver P having two parallel side bars 20 and 21' and an end bar 90pivoted in such manner that the driveris oscillated by oscillation ofthe armature 19., As shown in Fig. 1, when relay R is energized to closecontact 15-15 current flows through one portion of electromagnet E inone direction from battery D, thereby moving armature 19 in onedirection. When relay R- is reversed, however, to close contact 1515",current from battery I) flows through another portion of electromagnet Ein the opposite direction, thereby swinging armature 19 to the otherlimit of its stroke, and moving the driver P in the opposite direction.It will be plain, therefore, that when relayR is being operated inaccordance withany of the codes supplied to the trackway by codingdevice X, the driver P of the oscillator K will be swung to and fro atthe speed atWhich the relay It is operating. The oscillator K comprisesalso a plurality 1V and 1V each pivotally mounted on suitable bracketson the base 16 and disposed coaxially in such position that the sidebars 20 and 21 of the driver P extend through openings between thespokes of the wheels as best seen in Figs. 5 and 6. By means of helicalsprings 25, each of the side the driver P is attached to the rim of eachof'the wheels VJ at points adjacent the top of the wheel. driver P is atrest the two springs 25 acting upon-each of the'fly Wheels W arebalanced, so that the fly wheels then occupy positions of equilibrium.

oscillator K is being swung from side to side,

which is reversed insynchronism with the operation of relay B, isapplied to each of the fly wheels IV. The fly wheels are constructedwith different moments of inertia and the resiliency of the severalsprings 25'is so adjusted that each of the fly wheels IV is mechanicallyresonant-at the frequency of a different one of the codes supplied tothe trackway. For example, I will-assume that the fly wheel W ismechanically resonant at 80 cycles per minute. If the 80 cycle code,'hereinbefore termed the slow code, is supplied to the trackway, thedriver P will be operated at a frequency of 80 cycles per minute,-,.an;d

When the When the driver P of-the all) the wheels W will be made tooscillate, through the springs 25, at the same frequency. Since thewheel W is mechanically resonant at this frequency, the motion of thiswheel builds up to a considerable value and the wheel WV swings througha comparatively large 'arc in synchronism with the driver P. The wheelis resonant at 120 cycles per minute and the wheel W is mechanicallyresonant at 180 cycles per minute and it follows therefore that themotions of wheels W and WV caused by oscillation of the driver P at 80cycles per minute are comparatively small.

As best shown in Fig. 6, wheel W carries a movable contact 24 which isarranged to engage alternately with two fixed contacts 24 and 24 at thelimits of the motion of the wheel Vi when this wheel is being oscillatedat the frequency to which it is mechanically tuned. In similar mannerthe wheel V7 operates contacts 22-22 and 2222 and wheel W operatescontacts 2323 and 23-23.

From the foregoing explanation of the oscillator K, it will be apparentthat all of the contacts operated by the oscillator are normally openbut that when relay R operates at 80 cycles perminute in accordance withthe slow code, contact 22 operated by wheel W alternately engagescontacts 22 and 22 Under' these I conditions the contacts controlled bywheels 7 and W remain open. Similarly, if relay R is being operated at120 cycles per-minute or at 180 cycles per minute the contactscontrolled by wheels W and W respectively, are opened and closed inaccordance with the code, the contacts con trolled by the wheels whichare not resonant at the frequency at which the oscillator is operated,remainlngopen.

Each of the wheels WV is provided with damping mechanism here shown as apost 27 attached to the wheel and cooperating with two fixed dampingsprings 27. WVhen the wheel oscillates in either direction'a polished 1face of the post 27 engages one or the other of the damping springs 27.-The damping mechanism causes the amplitude of oscillation of each wheelto diminish rapidly when the corresponding code ceases so that theoscillator responds rapidly to code changes.

Furthermore the damping mechanism operates 1n a manner analogous toresistance in a tuned electrical circuit to broaden the tuning of thewheels so that each wheel wil respond to code frequencies slightlydifferent from the exact frequency to which the wheel is tuned. Stillanother function of the damping mechanism is to prevent operation of thecontacts of each wheel by frequencies of one third the frequency atwhich such wheel is resonant. V Y

Referring now again to Fig. 1, the oscillator K controlsthree'relays J J2 and J Each of the relays J and J comprises two "wires 37, 38 and thetwo halves respectively of windings 31 and 32 and is arranged to beslow-releasing. In explaining the operation of the apparatus Iwill-first assume that the slow code is being supplied to the-trackwayso that the relay R is operating at 80 cycles per minute. Under theseconditions the contacts 22-22 and 22.22 of oscillator K are alternatelyclosed and the remaining contacts of the oscillator remain open. Eachtime contact 2222 is closed, current flows from battery D, through wires33, 34, and 35, contact 22-22 wire 36, left-hand portion of primary 28of a transformer T, and wires 37, 38 and 39,. back to battery D. Whenthe contact 2222 of oscillator K closes, current flows from battery D,through wires 33, 34 and 35, contact 2222 of oscillator K, wire40,'righthand portion of primary 28 of transformer T and wires 37, 38and 39, back to battery D. It follows therefore that when the oscillatorK is being operated at cycles per minute, the direction of the currentsupplied to primary 28 of transformer T is periodically reversed. Thesecondary 29 of transformer T supplies energy to relay J through a rectifier 30 and it follows that this relay is energized when the slowcode isbeing supplied to the trackway.

' If the relay R isbeing supplied with the caution code, the contacts2323, and 2323 will be closed alternately, but the circuits ust tracedfor transformer T will be open. Each time contact 2323 is .closed,current flows from battery D, over wires 33, 34, 41, and 42, contact23-23 of oscillatorK, wire 43, winding 31 of relay J wires 44 and-45,left-hand portion of primary'28 of transformer T and 39 back tobattery'D; Each time'the contact 23 swings in the opposite direction,current from battery D flows through wires 33, 34, 41 and 42, contact23,23 of oscillator K, wire 46, winding 32 of relay J wires 47' and 48,right-hand portion of primary 28 of transformer T and wires, 37, 38 and39, back to battery D. It follows, therefore, that when the oscillator Kis being operated at- 120 cycles per minute in accordance with thecaution code, current is supplied alternately to the two windings ofrelay J in series with the two halves of the primary28 of transformer T.Under these conditions,

therefore, relay J is energized and relay J is energized also, althoughthe contacts operated by wheels W and V. of oscillator K remain open.Similarly, when the proceed code is being received, contacts 24.24 and24-24 are alternately closed and these con tacts are effective to supplycurrent to the two windings 31 and 32 of relay J in series with primary28 to transformed T over circuits which will be apparent from thedrawing. When the proceed code is being received, therefore, relays JandiJ are energized and relay J is deenergized.. L I Q r 54-54 of relayJ by contacts Relays J J 2 and J .m ay beutilized to control traingoverning meansin any suitable fashion andfor purposes of explanation Ihave here shown these relays as controlling signal lamps 56, 62, 65 and68. Assuming that the proceed code is being received, relays J and J areenergized, as shown in the drawing. Under these conditions, current frombattery D flows through wire 49, front contact -5O of relay J wire 51,back contact 52-52 of relay J wire 53, frontcontact wire 55, proceedlamp 56 and wires 57, 58, 59, 60, 38, and 39 back to battery D. Underthese conditions the proceed lamp 56 is lighted to indicate that theproceed code is being received. When the caution code is being received,relays J and J 2 are energized and relay J 3 is deenergized. Currentthen flows from battery D, over wire 49, front contact 5O5O of relay Jwire 51, front contact 52+52. of relay J wire 61, caution lamp 62, andwires 63, 58, 59, 60, 38 and 39, back to battery D. If the slow code isbeing received, relay J is energized and relays J and J are bothdeenergized and under these conditions the lamp is lighted, the circuitfor this lamp passing from battery D, through wire 49, front contact50-50 of relay J wire 51,back' contact 5252 of relay J wire 53, backcontact 54-54 of relay J wire 64, lamp 65, and wires 66, 59, 60, 38 and39 back to battery D. If no-code is being supplied to the trackway,.orif relay R is not being operated intermittently, or if for any otherreason the supply of current to relay J is interrupted, this relaycloses its back contact 5050", and thereby completes a circuit for thelamp 68 to indicate stop. The circuit for lamp 68 will be readilyunderstood from the drawing without tracing the circuit in detail. 1

In the modified form of apparatus shown in Fig. 2, the circuitsforrelays J and J 3 and for primary 28 of transformer controlled 23 and 24are the same as in Fig. 1. Contacts 2222"- and 22-22 of the oscillator Kare omitted, however, and the transformer T is provided with auxiliarycircuits controlled directly by the .relay R in place of the circuitscontrolled by contact wheel V in Fig. 1. Thus when the apparatus shownin Fig. 2 is receiving the caution or proceed codes, the operation isexactly connection with Fig. 1. is being operated in accordance with theslow the same as has already been described in WVhen the relay R codahowever, the contacts controlled by both wheels W and V areopen so thatrelays J 2 and J are deenergized. But each time contact 15-15 is closed,current from battery D flows through wire 33, contact 1515 wires and 71,back contact'72 of relay wire 73, back contact 74 of relay. J wires -7 5and 36,1eft-hand portion of primary 28 of transformer T, and wires 37,38, and 39,

below the frequencyof the slow code,

therefore, that when relay R is being operated atfthe frequency of theslow code, the alternating current induced in secondary 29 oftransformer T energizes relay J The parts maybe soproportioned that ifthe frequency of operation of relay R drops materially the amount of.energy supplied to relay J will not be suificientto keep this relayinits energized condition.

It will be plainthat the selection between the relays J J and J 3 inaccordance with the several codes is the same in Fig. 2 as in Fig. 1 andthe control of the signal lamps 68, 65, 62 and 56 by the relays J is thesame as in Fig. 1 and will be understood without further explanation.

The apparatus may be constructed to permit the oscillator K toperform-the functions ofthe relay R. For example, asshown in Fig. 7, thearmature 19 carries a contact finger 95which is electrically insulatedfrom the armature and which is arranged to swing alternatelyintoengagement with two fixed contacts 95 and 95 when the armatureisoscillated. With the oscillator constructed in thismanner, the parts maybe connected as shown in Fig. 8, from which it will be apparent that theelectromagnet E which operates ,the oscillator is connected directlywith the secondary of transformer Q. It follows that when the traincontrolling current supplied to the trackway is being periodicallyvaried,

the armature 19 of oscillator'K will be swung to and froat the frequencyof the variations in the trackway current.

The circuits for relays J and J 'andfor the primary 28 of transformer Tcontrolled by contacts 23 and 24 are thesameas in Figs.

1 and 2, and the operation of the apparatus in response to the proceedand caution code will be understood without further explanation.VVhen-the apparatus shown in-Fig. 8 is receiving the slow code, however,the armaturev 19 is driven at a rate so slow that the contacts operatedby 23 and 24 remain open, and relays J and J are deenergized.

Each time the armature swings in one direction, contact 95-95 is closedand current flows froinbattery D,through wires 33 and contact 95-9 5operated by'oscillator K, wire 71, back contact 7 20f relay J wire 73,

back contact 74, of relay J wires 75, 92 and 48, right-hand portion ofprimary 28 of transformer'T, and wires 37 and'38 back to battery D.VVhenthe armature 1-9- swings in the opposite direction, a :circuit is,completed 70 wires 81 and 40, right-hand portion from battery D, throughWires 33 and 91, contact 9595 operated by oscillator K, wire 77, backcontact 7 8 of relay J wire? 9, back contact 80 of relay J wires 81, 45and 36,

left-hand portion of primary 28 of trans former T, and wires 37 and 38back to bat,-

tery D. The periodically reversed current thus supplied to transformerprimary 28 during reception of the slow code energizes relayJ and underthese conditions lamp is lighted. The remaining lamps 68, 62 and 56 arecontrolled by the relays J J and J in the same manner as in Figs. 1 and2.

It will be plain from the foregoing, that with the apparatus constructedas shown in Fig. 8, the magnet E and its armature 19 not only drive thefly wheels of the oscillator, but also perform the functions of therelay R shown in Figs. 1 and 2. v

I make no claim, in the present case, to the structure of the oscillatorK, this device being claimed per se and in combination with apparatusfor intermittently supplying current to a load, in my copendingapplication Serial No. 426,565, filed on even date herewith.

Although I have herein shown and described only a few forms of railwaytraific controlling apparatus embodying my invention, it is understoodthatvarious changes andmodifications may be made therein within thescopeof the appended claims without departingfrom the spirit and scope of myinvention.

Having thus described my invention, what I claim is: I

1. Railway trafiic controlling apparatus comprising means for supplyingthe trackway with alternating current periodically varied at differentfrequencies, a plurality of train carried contacts operated by energyreceived from the trackway and selectively responsive to the frequencyof such periodic variations, a plurality of relays one con trolled byeach said contact and one of such relays controlled by all suchcontacts, and governing means controlled by said relays.

2. Railway traflic controlling apparatus comprising means for supplyingthe trackway with alternating current periodically varied at differentfrequencies, a train carried oscillator operated by energy received fromthe trackway and having a plurality of contacts selectively responsiveto' the frequency of such periodic variations, a plurality of relays onecontrolled by each of said contacts and one ofsuch relays beingcontrolled by all said contacts, and governing means controlled by saidrelays.

3. In combination, a source of alternating current, means forperiodically varying the current from said source at differentfrequencies, a relay receiving energy from the source and responsive tothe variations in such current but not to the current itself, anoscillatOr comprising a plurality of contacts each arranged to beoperated when and only when the relay is operating at a predeterminedfrequency which is different for each contact, a first relay arrangedto'be energized when any of said contacts is operating, other relayseach arranged to be energized when a predetermined one of such contactsis being operated, and governing means controlled by said relays.

4. In combination, a first relay, means for operating said first relayintermittently at different frequencies, a first contact arranged to beoperated when the relay is operating at one frequency, a second contactarranged to be operated when the relay is operating at a differentfrequency, a transformer, two other relays, means controlled by eachsaid contact for supplying periodic current to the primary of saidtransformer in series with a winding of an associated one of such otherrelays, a fourth relay receiving energy from the secondary of saidtransformer, and governing means controlled by said two other relays andby said fourth relay.

5. In combination, two contacts, means for at times operating onecontact and for at other times operating the other contact, two relays,a transformer, means effective when said one contact is operated tosupply pe riodic current to the primary of said transformer in serieswith a winding ofone relay, means effective when said other contact isoperated to supply periodic current to said primary in series with awinding of the remaining relay, a third relay receiving energy from thesecondary of said transformer, and indicating means controlled by saidthree relays.

6. Railway traffic controlling apparatus comprising means forflsupplyingthe track way with alternating current periodically varied atdiiferentifrequencies, a train car ried oscillator operated inaccordance with energy received from the trackwa'y and comprising twonormallyopen contacts arranged to be closed intermittently when and onlywhen said alternating current is being interrupted at a predeterminedfrequency, a relay having two windings, a circuit for one winding of therelay including one of said contacts, a circuit for the other winding ofthe relay including the remaining contact, and governing meanscontrolled by said relay.

7. Railway traffic controlling apparatus comprising means for supplyingthe track way with alternating current periodically varied at differentfrequencies, a train carried oscillator operated in accordance-withenergy received from the trackway and comprising two pairs of normallyopen contacts and means for alternately closing the contacts of one pairof contacts or the other depending upon the frequency of said"variations, a relay-comprising two'windings associated with each pairof contacts trans former; two circuits for each' relay each includingone Winding of such relay, one Contact of the associated pair, and aportion of the primary of said transformer; a third relay receivingenergy from the secondary of said transformer, and governing meanscontrolled by said three relays.

' 8. Railway traffic controlling apparatus comprising means forsupplying the trackcom risin means for sn 1 in the trackwa 23 b withalternating current periodically varied at different frequencies, a mainrelay receiv-- ing energy from the trackway and operating at a frequencywhich depends upon the fre quency of such variations, an oscillator controlled by said main relay and comprising a plurality of'contactsselectively responsive to the frequency of operation of the main'relay,a series of relays each controlled by an associated one of suchcontacts; an additional relay controlled by all said contacts, by saidmain relay, and by allthe relays in such series, and governing meanscontrolled by said additional relay andby the relays of said i series.

10. Railway traflic controlling apparatus comprisinga train carriedoscillator having an armature and a plurality of contacts selectivelyresponsive to the frequency of operation of said armature,nieans'located partly in thetrackway for operating said armature atdifierent frequencies, a first relay controlled by one said contact, asecond relay controlled by all said contacts, a nd governing meanscontrolled jointly by said two relays.

11, Railway traffic controlling apparatus comprising a train carriedoscillator having anarmature and a plurality of contacts selectivelyresponsive to the frequency of operation of said armature, means locatedpartly in the trackway for operating said armature at differentfrequencies, a first relay controlled by all said contacts, a pluralityof other relays each controlled by a different one of said contacts, andgoverning means controlled by said first relay andby said other relays'12. Railway traffic controlling apparatus comprising a train carriedoscillator having a movablearmature, means located partly in thetrackwayfor operating said armature at different frequencies, aplurality of contacts operated mechanically by said armature andselectively responsive to the frequency of operation of such armature,an additional contact operated by said armature, and governing meanscontrolled by all said contacts.

13. Railway traffic controlling apparatus comprising a train carriedoscillator having a movable armature, means located partly in thetrackway for operating said armature at different frequencies, aplurality of contacts operated mechanically by said armature andselectively responsive to the frequency of operation of such armature, aplurality of relays each controlled by a different one of said contacts,an additional relay controlled directly by said armature, and governingmeans controlled by all said relays.

14. Railway traffic controlling apparatus comprising means for supplyingthe trackway with alternating current periodically varied at differentfrequencies, a train carried oscillator having an armature operated byenergy received from the trackway at a frequency which depends upon thefrequency of variationof the trackway current, a plurality of contactson said oscillator selectively responsive to the frequency of operationof said armature, a first relay controlled by all said contacts, aplurality of other relays each controlled by a different one of saidcontacts, and governing means controlled by said first relay and by saidother relays.

15. Railway traflic controlling apparatus comprising means forsupplying-the trackway with alternating current periodically varied atdifferentfrequencies, an oscillator having a plurality of contactsselectively responsive to the frequency of the variations in thetrackway current, a first relay controlled by all said contacts, aplurality of other relays each controlled by a different one of saidcontacts, and governing means controlled by said first relay and by saidother relays.

16. In combination, a source of alternating current periodically variedat difl'erent frequencies, an oscillator controlled by energy receivedfrom said source and comprising a plurality of contacts selectivelyresponsive tothe frequency of the variation in such current,a firstrelaycontrolled by all said contacts, a plurality of other relays eachcontrolled by a different one of said contacts, and governing meanscontrolled by said first relay and by said other relays.

In testimony whereof I affix my signature.

' ANDREW J. SOR-E'N SEN.

